Well guys put the car on a rolling road at the weekend, the only engine mods are a PD160 intake & Green Cotton Filter.

Can anyone explain why the bhp is greater but the torque figure is lower than the standard figures?

Standard - 130 bhp, 230 lbs.ft

Mine - 144.6 bhp, 226 lbs.ft

What is this correction factor everyone talks about?

It's also interesting where your peak power is at, torque being at 2200rpm and bhp at 4200rpm. Peak torque on a standard map is 1900. I didnt think the standard map would have pulled that well up the revs.

My car was 127.8bhp as standard

Had you hooned it over to the rolling road? Maybe you had some heat soak effecting the torque spike?

that amount of BHP isn't unheard of on a stock map.

I'm also a bit surprised at the position of your torque peak though.

The 'correction factor' is where the dyno op can put anything he likes to make the final figure whatever he wants!

The reason your peaks are shifted is likely to be because the cam timing is slightly different, if you look carefully at the drive pulley on the end of your cam you'll find it has slotted holes and lock bolts like a vernier pulley, these are there so that the dealer can adjust it when he changes belts or replaces head gaskets because the PD engine is VERY sensitive to cam timing.

Most independent garages do not bother doing this when they change a cambelt because it requires that you have a dial gauge set up on the cam and peak lift specs to adjust it to, most fitters can barely read a book let alone a dial gauge!

See here for more info:

http://www.autospeed.com/cms/A_112521/article.html

Good to know that the PD160 intake and cotton filter make such a huge difference BTW

Edited 29 August, 201114 yr by sepulchrave

Wasn't a particularly fast drive, just 70mph on the motorway and there was 6 dyno runs before mine so it had plenty of time too cool down. I didn't expect the PD160 Intake to make a huge difference tbh, maybe a few bhp. Is it a bad thing having slightly different cam timing?

You didn't read the article I linked, tl;dr?

You are correct sir, fitting the PD160 intake and a cotton filter will usually only lose you a few BHP, so no biggie there, but the loss of filtration efficiency would worry me more, you don't want all that fine abrasive dust getting into your engine via a delicate VG turbo so that when it mixes with the fuel you get a nice light grinding paste.

You didn't read the article I linked, tl;dr?

You are correct sir, fitting the PD160 intake and a cotton filter will usually only lose you a few BHP, so no biggie there, but the loss of filtration efficiency would worry me more, you don't want all that fine abrasive dust getting into your engine via a delicate VG turbo so that when it mixes with the fuel you get a nice light grinding paste.

Just read the article, very interesting read, think i'll have a look and see where mine is set. I do my servicing every 7000 miles, I take the filter out, wash it thoroughly and use the pressurised air gun we have to dry it, then give it a couple of hours to dry completely. I don't tend to oil it however I might oil it lightly this time too see if there is much difference.

Interesting read on the cam timing etc.

I also never knew that's exactly how the injectors worked!

Just had my cambelt done recently but everything seems good on mine. Still get really good economy. And torque seems to be right on the button with the big "lump" of "go" at around 1900-2000rpm.

Phil